He said: "It's important because the name of the company is Microsoft," he said "It was a fundamental part of the founding principles: we were a software company.

"And yet: Xbox, Surface and now the phone, and we have a profile that will end up being mixed in the future. That's a pretty fundamental change."

United we stand

Ballmer also owned up to a few mobile missteps during his tenure as Bill Gates' successor, including the company's hesitance to unite the company's hardware and software strategies.

He added: "In the last 10 years, there are things that didn't go so well. We would have had a strong position in the phone market. The thing I regret is that we didn't put hardware and software together quicker."